The present invention relates to a storage container for a magnetic tape cartridge, more particularly to a storage container provided with means for preventing rotation of tape hubs provided in the magnetic tape cartridge.
A conventional storage container of this type is disclosed, for example, in U.S. Pat. No. 3,272,325. This container is composed, as shown in FIG. 1, of a receptacle container body 1 made of polystyrene resin, acrylic resin, or the like and a lid 2, which is pivotally supported on the body 1 to permit opening and closing the body 1 and a magnetic tape cartridge 3 is inserted from its front side into the pocket 4 provided on one side of the lid 2. When the lid 2 is closed, two plate-like lugs 5 which project from the bottom wall 1a of the body 1 are adapted to engage with respective driving shaft insertion holes of the hubs 6 to prevent rotation of the hubs 6, by which the magnetic tape wound on the hubs 6 is prevented from being loosened in the magnetic tape cartridge 3.
The action of preventing the rotation of the hubs 6 by means of the lugs 5 is shown in FIG. 2. It is well known that each of the hubs 6, which are of synthetic resin, is standardized to have six protruding hub-toothings 9 on its inner circumferential surface. Each of the hubs 6 is rotatably supported with play relative to the driving shaft insertion hole 10 of the magnetic tape cartridge 3. Each lug 5 for preventing the rotation of the hub 6 is formed at its top end portion into knife edges 5a and 5b, so that even when an end portion thereof comes into collision with the projecting end face of one of the hub-toothings 9, the hub 6 can slide the top end portion of the lug 5 resulting in engagement in the hub 6. Thus, as shown in FIGS. 2a and 2b, either one end 5a or the other end 5b of the lug 5 rests in the space between the adjacent hub-toothings 9 to prevent free rotation of the hub 6. However, when both ends 5a and 5b of the lug 5 come to the respective centers of the projecting ends of the two hub toothings 9a and 9d, as shown in FIG. 2c, it sometimes occurs that said two ends 5a and 5b wedge into the end portions of the hub-toothings 9a and 9d.
On the other hand, the magnetic tape cartridge of this kind is put in a storage container by means of an automatic package machine when it is supplied from the manufacturing process. In this case, the lid 2 is forcibly closed by the automatic package machine even under the state where the hub-toothings 9a and 9d are caught by the knife edges 5a and 5b, the hub 6 is pushed up by the knife edges 5a and 5b in the magnetic tape cartridge 3 and is held in a position spaced up from the bottom surface of the cartridge, as shown in FIG. 3. When the container is carried under the above state, being rattled, the magnetic tape 8 wound on the hub is partly let down to assume a stepped form, or a roll of the magnetic tape 8 taken up on the hub 6 slides down from the hub 6, thereby providing a cause for the defective running of the magnetic tape at the time of the use of the magnetic tape cartridge. These were the drawbacks experienced with the conventional storage container for the magnetic tape.
The above problems come to the notice of the consumer when he is about to use the magnetic tape cartridge after it is packed and delivered from the factory. There is another defect that, if, in an extreme case, the lugs 5 of the container strongly wedge into the hub, the lid 2 of the storage container is hard to open.
The present inventors have attempted to eliminate the above defects by modifying the shape of the lug 5 for preventing the rotation of the hub 6. The first trail was to bend the plate like lug 5 into an angled cross-sectional form, as shown in FIGS. 4a and 4b. According to said contrivance, as the lug 5 is bent at an angle of about 150.degree. to form the two angled sides, even when one end 5a of the lug 5 comes into collision with one of the hub toothings 9, the hub 6 is slid in a direction of the side 5a without causing wedging, and on the other hand the other end 5b is always received between the opposed hub toothings 9c and 9d. However, even by said contrivance, there is a possibility that, when the magnetic tape cartridge 3 per se set in the lid 2 is displaced to either right or left in the pocket 4 and when idle movement of the hub 6 is added, the lug may be brought to a state shown in FIG. 4b, by which the two ends 5a and 5b of the lug 5 wedge into the hub toothings 9a and 9c.
As a result of the study specially on the shape of the lug for preventing the rotation of the hub through the above trial-and-error, the present invention has been developed by constituting a projection for preventing the rotation of the hub by a columnar boss with a corn top portion and the first and second engaging keys protruding generally radially from said boss, thereby eliminating the above defects inherent in the conventional storage container.